Northern California is currently under a Coastal Flood Advisory issued by the National Weather Service (NWS), which remains in effect through early Tuesday morning. This advisory comes in response to a combination of unusually high tides, strong onshore winds, and elevated surf conditions that pose a risk of minor to moderate flooding along the region’s coastal areas.
In this article, we’ll break down what this means, who’s affected, what to expect, and how residents can stay safe
đź“Ť What Is a Coastal Flood Advisory?
A Coastal Flood Advisory is issued when coastal flooding is possible or expected—not from heavy rain, but due to tide levels, storm surge, or wave action. These events can lead to water encroaching on low-lying roads, beaches, harbors, and vulnerable infrastructure.
🗺️ Areas Affected
.The advisory applies to much of Northern California’s coastline, including but not limited to:
- San Francisco Bay Area
- Marin, Sonoma, and Mendocino Counties
- Humboldt and Del Norte Counties
- Monterey Bay and Santa Cruz
- Low-lying sections of Pacific Coast Highway (Highway 1)
Particularly vulnerable are harbors, marinas, beach communities, and estuaries.
🌊 What’s Causing the Flooding?
1. King Tides
Northern California is currently experiencing King Tides, which are seasonal high tides that occur when the Earth, moon, and sun align to produce the highest gravitational pull on the ocean.
2. Elevated Surf
A Pacific storm system has generated large swells moving toward the coast, with waves reaching up to 10-15 feet in some areas. These swells push water inland, exacerbating the effects of high tides.
3. Onshore Winds
Strong winds blowing from the ocean onto land (onshore flow) are trapping water against the coast, making drainage slower and increasing the risk of flooding.
⏰ Timeline of the Advisory
The advisory is expected to remain in effect until early Tuesday morning (July 22, 2025). The highest risk periods are during high tide cycles, especially:
- Monday at 9:30 AM – 11:30 AM
- Monday night between 10:00 PM – 12:00 AM
Tide levels may rise 2 to 4 feet above normal, enough to impact coastal roads and infrastructure.
Expected Impacts
- Minor flooding of coastal roads and parking lots
- Overflow in low-lying backyards and basements
- Disruption to harbor operations and boat launches
- Increased beach erosion
- Hazardous surf conditions for swimmers and surfers
Areas of Special Concern:
- Embarcadero in San Francisco
- Venice Beach in Half Moon Bay
- Bodega Bay Docks
- Humboldt Bay shoreline
⏰ Timeline of the Advisory
The advisory is expected to remain in effect until early Tuesday morning (July 22, 2025). The highest risk periods are during high tide cycles, especially:
- Monday at 9:30 AM – 11:30 AM
- Monday night between 10:00 PM – 12:00 AM
Tide levels may rise 2 to 4 feet above normal, enough to impact coastal roads and infrastructure.
🚧 Expected Impacts
- Minor flooding of coastal roads and parking lots
- Overflow in low-lying backyards and basements
- Disruption to harbor operations and boat launches
- Increased beach erosion
- Hazardous surf conditions for swimmers and surfers
Areas of Special Concern:
- Embarcadero in San Francisco
- Venice Beach in Half Moon Bay
- Bodega Bay Docks
- Humboldt Bay shoreline
🧠Safety Tips for Residents and Travelers
“If you don’t have to be near the coast during the advisory period, don’t go. Stay informed and stay safe.” — NWS Spokesperson
Here are some ways you can prepare:
- Avoid Beachfront Roads during high tide periods.
- Secure Boats & Docks in advance.
- Move Vehicles to Higher Ground if parked near low-lying areas.
- Do Not Walk or Drive Through Floodwater.
- Just 6 inches of water can knock over an adult.
- 12 inches can move a small vehicle.
- Stay Updated through local news, NOAA radio, or NWS updates.
How to Stay Informed
You can track tides, advisories, and storm systems through:
National weather service-california
Local emergency alerts or Wireless Emergency Alerts (WEA) on your smartphone
- smartphone
🌤️ Looking Ahead
Meteorologists expect conditions to gradually improve by late Tuesday, as the current storm system moves eastward and high tides return to normal. However, residents are urged to remain vigilant, especially with more King Tide events forecasted in August and December this year.
Final Thoughts
Coastal flood events like this one are increasing in frequency due to climate change and rising sea levels. While this advisory may only cause minor flooding, it’s a reminder of how vulnerable our coastal communities are to changing ocean conditions.
If you’re in or around Northern California’s coastline this week, exercise caution, avoid unnecessary travel during high tide, and follow all safety advisories. It’s better to wait than to wade.
Stay dry. Stay informed. Stay safe.